login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A306212 Numbers that are the sum of squares of three distinct positive integers in arithmetic progression. 2
14, 29, 35, 50, 56, 66, 77, 83, 93, 107, 110, 116, 126, 140, 149, 155, 158, 165, 179, 194, 197, 200, 210, 219, 224, 242, 245, 251, 261, 264, 275, 290, 293, 302, 308, 315, 318, 332, 341, 350, 365, 371, 372, 381, 395, 398, 413, 428, 434, 435, 440, 450, 461, 462, 464, 482, 491, 504, 509, 515, 525, 530, 539, 557, 560, 563, 579, 590, 594, 596 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..70.

EXAMPLE

35 = 1^2 + 3^2 + 5^2, with 3 - 1 = 5 - 3 = 2;

371 = 1^2 + 9^2 + 17^2, with 9 - 1 = 17 - 9 = 8. Also 371 = 9^2 + 11^2 + 13^2, with 11 - 9 = 13 - 11 = 2.

PROG

(PARI) for(n=3, 600, k=sqrt(n/3); a=2; v=0; while(a<=k&&v==0, b=(n-3*a^2)/2; if(b==truncate(b)&&issquare(b), d=sqrt(b); if(d>=1&&d<=a-1, v=1; print1(n, ", "))); a+=1))

(PARI) w=List(); for(n=3, 600, k=sqrt(n/3); for(a=2, k, for(c=1, a-1, v=(a-c)^2+a^2+(a+c)^2; if(v==n, listput(w, n))))); print(vecsort(Vec(w), , 8))

CROSSREFS

Cf. A000290, A000378, A000408, A085317, A120328, A292313, A306213, A306214.

Sequence in context: A305662 A174070 A045527 * A041384 A041382 A047725

Adjacent sequences:  A306209 A306210 A306211 * A306213 A306214 A306215

KEYWORD

nonn

AUTHOR

Antonio Roldán, Jan 29 2019

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 16 01:32 EST 2019. Contains 330013 sequences. (Running on oeis4.)